(function (designWidth, maxWidth) {
  var doc = document,
      win = window;
  var docEl = doc.documentElement;
  var tid;
  var rootItem, rootStyle;

  function refreshRem() {
      var width = docEl.getBoundingClientRect().width;
      if (!maxWidth) {
          maxWidth = 540;
      }
      ;
      if (width > maxWidth) {
          width = maxWidth;
      }
      //与淘宝做法不同，直接采用简单的rem换算方法1rem=100px
      var rem = width * 10 / designWidth;
      //兼容UC开始
      rootStyle = "html{font-size:" + rem + 'px !important}';
      rootItem = document.getElementById('rootsize') || document.createElement("style");
      if (!document.getElementById('rootsize')) {
          document.getElementsByTagName("head")[0].appendChild(rootItem);
          rootItem.id = 'rootsize';
      }
      if (rootItem.styleSheet) {
          rootItem.styleSheet.disabled || (rootItem.styleSheet.cssText = rootStyle)
      } else {
          try {
              rootItem.innerHTML = rootStyle
          } catch (f) {
              rootItem.innerText = rootStyle
          }
      }
      //兼容UC结束
      docEl.style.fontSize = rem + "px";
  };
  refreshRem();

  win.addEventListener("resize", function () {
      clearTimeout(tid); //防止执行两次
      tid = setTimeout(refreshRem, 0);
  }, false);

  win.addEventListener("pageshow", function (e) {
      if (e.persisted) { // 浏览器后退的时候重新计算
          clearTimeout(tid);
          tid = setTimeout(refreshRem, 0);
      }
  }, false);

  if (doc.readyState === "complete") {
      doc.body.style.fontSize = "16px";
  } else {
      doc.addEventListener("DOMContentLoaded", function (e) {
          doc.body.style.fontSize = "16px";
      }, false);
  }
})(375, 750);